Knife rest for sharpening knives



June 6, 1939. M v MQELLER 2,160,979

KNIFE BEST FOR SHARPENING KNIVES Filed Dec. 30, 1935 Mueller, fleemi-2e); Qdhebn used,

ZhM W i/ WITNESSES; fiwm Patented June 6, 1939 UNITED STATES PATENTOFFICE KNIFE BEST FOR SHARPENING KNIVES Tempelhof, Germany ApplicationDecember 30, 1935, Serial No. 56,744 In Denmark January 4, 1935 3Claims.

This invention relates to a knife-rest, having a grinding face on whicha knife can be ground for sharpening. The knife has to be uniformly heldat a predetermined angle to the grinding face in order that the correctcutting angle is given to the cutting edge from both sides. It is,however, extremely difficult, to correctly and uniformly maintain thisangle when the knife is held in the free hand, so that the knife isgenerally not only not sharpened correctly but scratched on its sidefaces, this being very inconvenient especially for chromed knivespolished to brilliant polish.

These inconveniences are obviated, according to the invention, whengrinding knives or the like on the knife-rest, in that in front of thegrinding face a guide groove for the knife back is arranged.Consequently it is not longer necessary to preserve the sharpening anglewith the free hand, as, by insertion of the knife back into the guidegroove'the correct angle for the sharpening is automatically adjustedand uniformly preserved, so that any unskilled person can accuratelygrind a knife on the knife rest. Scratching of the side faces of theknife is also excluded. The sharpening is automatically effected only atthe cutting edge so that the chrome side faces of a knife are notinjured by the sharpening. The bottom of the guide groove or the sideface of the guide groove facing the grinding face is preferably domed,for instance bulged outwards at the middle, in order that the knifeback, even if it is curved, bears during the grinding, at one point andcan be easier moved to and fro. The knife, when moving over the bulgedportion, is further slightly lifted and lowered, so that it moves overseveral portions of the grinding face adjusted at the same height, andthe grinding stone or the like wears more uniformly. The grinding facemay consist for instance of grind stone or of a support of wood or othersuitable material covered with carborundum or a similar substance. Thegrinding face may be, if desired, mounted so that it can rock about anaxle, in order that it can be adjusted at difierent angles to therebyalter the grinding angle or to adapt the same to special conditions. Inorder that the grinding angle remains as uniformly as possible, the samefor wide and for narrow knives, the grinding face may be bulgedaccording to the radius of a circle or according to a certain curve, thecurve of the logarithmic spiral being preferably employed. Two grindingfaces, lying back to back may be preferably arranged mutuallysymmetrical, each one having a guide groove in front of it, whereby aknife rest is produced on which on the right hand side the one side faceand on the left hand side the other side face of a knife can besharpened. Or both grinding faces each with its guide groove arearranged symmetrically opposite, a free upwardly projecting rib beingprovided as separating partition. Grinding faces may further be arrangedone at either side of a single guide groove. An especially simplearrangement is obtained if guide grooves are arranged, one at eitherside of a grinding face. The grinding faces may be removable in orderthat they can be interchanged or reversed or adjusted in thelongitudinal and transverse directions. With this object in view aholding bar, or a bar adapted to be inserted either below or above thegrinding stone is for instance provided, enabling especially adjustingin vertical direction. A holding face may be arranged at the side of thegrinding face on one side or on both sides of the same, by means ofwhich the knife-rest can be held in one hand or fixed on the table topby screws.

Several embodiments of the invention are illustrated by way of examplein the accompanying drawing in which:

Fig. 1 shows in end view, partly in section a knife-rest with grindingface and. guide groove for the knife back in front of the grinding face.

Fig. 2 shows in end view partly in section a knife-rest, the grindingface of which is oscillatably mounted.

Fig. 3 shows in end view partly' in section a knife-rest having aconcave grinding face and adapted to be combined with a secondknife-rest as indicated in dash lines and in dot-dash linesrespectively.

Fig. 4 is a section on line A-B of Fig. 3.

Fig. 5 shows in end View a knife-rest with two grinding faces and acommon guide-groove between the grinding faces.

Fig. 6 shows in end View, partly in section a knife-rest with onegrinding face and two guidegrooves, one on each longitudinal edge of thegrinding face.

Fig. 7 shows in end view partly in section a knife rest with twogrinding faces, one guide groove being arranged in front of eachgrinding face and a holding face on one side.

Fig. 8 shows in top plan View part of the knife rest shown in Fig. 7.

A knife-rest of simple form of construction consists of a vertical backwall I, recessed on the front side so that a box-shaped bed for a grindstone 2 is formed as shown in Fig. 1. The back wall I has at the top atop bar 6 and on the bottom a socle 3 with guide groove 5-. The socle 3is fixed on a base plate 8 which is so long that it projects from thesocle 3 at one side or at both sides and can be securely held with ahand or be fixed on a table top by screws.

The back wall i of the knife-rest shown in Fig. 2 is oscillatablymounted on a horizontal axle 5 so that, to alter the grinding angle, thea grinding surface can be adjusted at any desired angle.

In order to preserve the same grinding angle, independently on the widthof the knife to be sharpened, the grinding face i (Fig. 3) is concaveand curved according to a logarithmic spiral. In order that the knifeback, even if it is curved, bears as far as the possible and is guidedonly at one point, the bottom 3 of the guide groove is domed, as shownin Figs. 3 and 4. Owing to the bulged surface of the bottom of the guidegroove the knife is lowered and lifted during the grinding and thegrinding face is. more uniformly worn. All the parts of the knife-restshown in Fig. 3 may be repeated symmetrically to the line aa so that (asindicated in dash lines) the grinding face It, a guide groove ii and asocle 9 are added. In this instance a knife-rest is produced on which onthe right the left side of the knife edge and on the left the right sideof the knife edge can be sharpened. If, however, all parts of the kniferest shown in Fig. 3 are again repeated symmetrically to the dash-dotline b-b, a grinding face l3, guide groove Hi and socle l2 are added,and it is possible to sharpen with this device also both sides of aknife edge. In this instance, a guide rib 15 projects between the twoguide grooves 3 and it.

As shown in Fig. 5 a single guide groove 15 can be substituted for thetwo guide grooves i and Hi. The bottom of guide groove l5 may beconvexly curved, same as that of guide groove 4, so that the grindstones ll can be adjusted in vertical direction on this rest uponremovable bars I8. If these bars I5 have been removed, the grid stonesI! drop and the bars 58 can be inserted on top of the grind stones.

The knife rest shown in Fig. 6 has one grinding face 2| and two guidegrooves l9, 2E! one at each side of the grinding face.

In the knife-rest shown in Fig. '7 the concave grind stones I8, havingconcave grinding faces 1, are mounted on a rest body pressed from apiece of artificial resin, for instance Bakelite, this body having twoguide grooves 25. The grind stones Ill are securely held on theknife-rest by means of a top bar 23 removably fixed by a screw bolt 22.The knife-rest has at the righthand side an extension 25 adapted toserve as handle or to be fixed on a table top. As shown in Fig. 8 theside walls of grooves 26 may be convex in order that the knife backbears only at one point and the knife edge is slightly shifted invertical direction during the sharpening.

V'Jhat is claimed is:

1. In a knife sharpener, an elongated block having a flat bottom adaptedto be pressed and securely held on a support, a grind stone fixed on thefront face of said block and having a concaved surface, an extension onthe front side of said block having an elongated groove extendingsubstantially parallel to the outer surface of said grind stone andadapted to hold the back of a knife to be sharpened, said surface of thegrind stone adapted to guide at the correct grinding angle the cuttingedge of the knife to be sharpened, a portion of the block carrying thegrind stone being oscillatably mounted on a hori- Zontal axle to adjustthe outer surface of the grind-stone at different angles to the guidegroove to vary the adjustment of the grinding angle.

2. In a knife sharpener, an elongated block having a flat bottom adaptedto be pressed and securely held on a support, a grind-stone fixed on thefront face of said block and having a concaved surface, an extension onthe front side of said block having an elongated groove extendingsubstantially parallel to the outer surface of said grind-stone andadapted to hold the back of a knife to be sharpened, said surface of thegrind-stone adapted to guide at the correct grinding angle the cuttingedge of the knife to be sharpened, the outer surface of the grindstonebeing concaved perpendicularly to the direction of movement of the knifeto be sharpened to maintain a constant grinding angle for knives ofdifierent widths.

3. In a knife sharpener, an elongated block having a fiat bottom adaptedto be pressed and securely held on a support, a grind-stone fixed on thefront face of said block and having a concave surface, an extension onthe front side of said block having an elongated groove extendingsubstantially parallel to the outer surface of said grind-stone andadapted to hold the back 7 of a knife to be sharpened, said surface ofthe grind-stone adapted to guide at the correct grinding angle thecutting edge of the knife to be sharpened, a shoulder on the block uponwhich the grind-stone is removably placed, and a removable top barengageable with the grindstone for holding the same in position.

ELSE MOELLER, min KNUPFER, Legal Representative of Morten Vz'lhelmMoeller,

Deceased.

